Usually, an outboard motor is mounted to a transom of a ship via a swivel bracket. In this case, the outboard motor is rotatably mounted to the swivel bracket. For example, a steering handle with a throttle grip to adjust engine output at a distal end typically extends from a front lower portion of an engine forward. Horizontally steering this steering handle changes a direction of the entire outboard motor, thus ensuring the steering of a ship.
There has been provided a mounting structure for an outboard motor, for example, like the following outboard motor according to Patent Document 1. A drive shaft housing, which includes a drive shaft in an internal exhaust passage, is disposed below an engine. The drive shaft housing is rotatable supported to a rotating support portion of a swivel bracket. A resilient body is mounted to an outer peripheral surface of the drive shaft housing. A handle bracket to support a base of the steering handle is mounted to an outer peripheral surface of this resilient body. A bracket cover to which the swivel bracket is mounted is slidably mounted to an outer peripheral surface of the handle bracket via a bush. This mounting structure reduces a transmission of engine vibrations to the steering handle side and a ship side by the resilient body.
An outboard motor according to Patent Document 2 includes a resilient member interposed between a steering handle and an engine side. This resilient member is configured to be freely vibratable in a clearance between the steering handle and the engine side. The outboard motor further includes an abutting portion, which can be brought into abutment with the engine side, on a steering handle side. This mounting structure minimizes vibrations transmitted from the engine to the steering handle.    Patent Document 1: Japanese Laid-open Patent Publication No. 2002-347696    Patent Document 2: Japanese Laid-open Patent Publication No. 11-189199
Conventionally, as described above, a steering function and a vibration damping function are obtained by a mount shape, approximately cylindrical shape, of the resilient body or the resilient member. In this case, a spring constant in a rotation direction of the resilient body is generally preferable to be large in terms of the steering function. In terms of the vibration damping function, the spring constant is generally preferable to be small. Reducing the spring constant of the mount (resilient body) to reduce vibrations causes a problem of making responsiveness or operational feeling of the steering worse. Thus, a balance between the functions conflicting in the approximately cylindrical mount shape needs to be considered. Therefore, achieving further improvement both in the vibration damping function and the steering performance is not easy.